The present disclosure relates to semiconductor devices and, more particularly, to three-dimensional (3D) semiconductor memory devices including three-dimensionally arranged memory cells.
Semiconductor devices have been highly integrated to provide high performance and low costs. The integration density of semiconductor devices may directly affect the costs of the semiconductor devices, so highly integrated semiconductor devices have been demanded. An integration density of a conventional two-dimensional (2D) or planar memory device may be mainly determined by an area which a unit memory cell occupies. Therefore, the integration density of the conventional 2D memory device may be greatly affected by a technique of forming fine patterns. However, since extremely high-priced apparatuses are needed to form fine patterns, the integration density of 2D memory devices continues to increase but is still limited.
Three-dimensional (3D) semiconductor devices including three-dimensionally arranged memory cells have been developed to overcome the above limitations. However, production of 3D semiconductor memory devices may be expensive as compared with 2D semiconductor memory devices and may cause concerns regarding providing reliable device characteristics.